1. Field of the Invention
The present invention relates to a process for production of an impact-modified polycarbonate composition and/or generally molding composition filled with carbon nanotubes, wherein the degradation of the molecular weight of the polycarbonate during compounding is improved as compared with certain processes known in the art.
2. Description of Related Art
WO-A 2001/92381 describes a process for the incorporation of CNT agglomerates into a polymer matrix by hydrodynamic loading. Breaking up of the agglomerates is achieved in this way.
WO-A 2003/079375 claims polymer material that shows mechanically and electrically improved properties by the addition of carbon nanotubes. The carbon nanotubes are cleaned of catalyst residues and of catalyst support by washing. A process for the production of such reinforced materials by incorporation into the melt is also claimed.
WO-A 2005/015574 discloses compositions containing organic polymer and carbon nanotubes (referred to herein as “carbon nanotubes” or “CNT”) which form rope-like agglomerates and contain at least 0.1% impurities. The compositions are distinguished by a reduced electrical resistance and a minimum notched impact strength. A process for the incorporation of CNT, wherein high shear forces are applied, and a process using a masterbatch are also disclosed.
U.S. Pat. No. 5,591,382 discloses polymer compositions containing carbon fibrils, at least some of which are present in the form of agglomerates. The agglomerates do not exceed a size of 35 μm. The composition is distinguished by reduced electrical resistance in combination with a minimum notched impact strength. A polymer composition in which agglomerates of the carbon fibrils are broken up by an incorporation process using shear forces, is also disclosed.
U.S. Pat. No. 6,265,466 discloses a polymer composition composed of polymer material and CNT which offers electromagnetic shielding, and a process the production thereof. The process involves the use of shear forces, e.g. in extrusion, to orientate the CNT.
JP-A 2006-083195 discloses polycarbonate compositions containing CNT and polyolefins. A process for the production thereof in which first of all the polyolefin is mixed with the CNT and then the polycarbonate added, is claimed.